Stabilization of soybean oils with p-toluene sulfonic acid



Patented Jan. 29, 1952 STABILIZATION OF SOYBEAN OILS WITH P-TOLUENE SULFONIC ACID Arthur W. Schwab, Cyril D. Evans, and John C. Cowan, Peoria, 111., assignors to the United States of America as represented by the Secretary of Agriculture No Drawing. Application March 30, 1951, Serial No. 218,514

2 Claims. (01.99-103) (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) The invention herein described may be manufactured and used by or for the Government of theUnited States of America for governmental purposes throughout the world without the pay-- ment to us of any royalty thereon.

This invention relates to the treatment of soybean oil, alone or mixed with related materials; by adding p-toluene sulfonic acid thereto as a stabilizer to prevent oxidative deterioration of the oil.

Glyceride oils of animal or vegetable origin are prone to deteriorate more less rapidly upon storage. This deterioration is a familiar phenomenon. It is mainly due to oxidative processes which are difllcult to control and which are frequently unpredictable in nature and effect. Difllculty of control is largely due to the presence of small quantities of substances, such as metals, which act.as catalysts for the autoxidation of the oil. Soybean oil is particularly subject to this deterioration.

We have found that minor amounts of D-toluene sulfonic acid, added to soybean oils, has a marked stabilizing efiect upon the oil against oxidative deterioration. It is effective in inhibiting autoxidation in the presence of the catalytic substances previously mentioned and also even in the presence of added amounts of metals such as iron and copper. Its eflect upon soybean oil is peculiar, the reason therefor being not well understood. For example, the addition of this substance tooils, such as cottonseed oil, seems to accelerate, rather than inhibit, oxidative deterioration.

In general, according to the invention, the

p-toluene sulfonic acid is merely mixed into the oil. The amount added may vary from 0.001 to 0.1 percent by weight. The acid may be incorporated in the oil at any desired stage in the conventional treatment of the oil. It is convenient to make the addition just prior to the deodorization step in the case of refined oils.

The following experimental data illustrate the invention. Samples of soybean oil were treated with p-toluene sulfonlc acid in the amounts shown in the table. samples of cottonseed oil treated with p-toluene sulfonic acid and samples of untreated controls are also included in the tabulation. The oils were evaluated by the known modified Swift Stability test. This test provides the peroxide values after the samples are blown with air for 8 hrs. at 208 F. (A. O. M. values). The A. O. M. values are measures of the oxidative stability of the oil, a low value indicating relative stability.

We claim:

. 1. Soybean oil containing p-toluene sulfonic acid as a stabilizer.

2. The oil of. claim 1 in which the stabilizer is within the range of 0.001 to 0.1 percent based on the weight of the oil.

ARTHUR W. BCHWAB. /CYR.IL D. EVANS.

JOHN C. COWAN.

No references cited.

To illustrate the effect. 

1. SOYBEAN OIL CONTAINING P-TOLUENE SULFONIC ACID AS A STABILIZER. 